The present invention takes its place in the field of mixing, consolidation and compaction technologies and concerns a modular system of multipurpose rods for drilling soils.
Various procedures are known for the consolidation of the soil through the formation of cylindrical columns of consolidated soil, based on the mixing of particles of the soil itself with binders, usually cemented mixtures.
A traditional procedure, through which a mainly mechanic mixing is carried out, uses the rotating movement of tools (see FIG. 1) able to dig and breaks up the soil through appendixes which radially extend to the axis of the tool itself. The soil so broken up is kneaded with a low-pressure (1-2 MPa) cemented mixture pumped through openings obtained on the tubular shaft right under the blades.
A known variant of the described procedure is to use higher pressures for the cemented mixtures. This technique, by using the combination of the mechanical action of the disintegrating gears of the tool and of the kinetic energy of the pressurized jets, differs for a substantial execution speed, with considerable economic advantages.
There are variants of these techniques which require a double line of cemented mixtures. In addition to the outputs on the shaft of the tool which interact with the disintegrating gears, there are others on the upper parts of the blades which treat a diameter of soil bigger than the one treated by the mechanical disintegrating gears. This increase of the treated diameter when it is not requested for all the depth, makes it necessary a double supply.
Another technology taken into consideration by the present invention is the one of compacting piles. From the European patent EP 0 228 138 it is known an excavation and compaction equipment for the construction of compacting piles. In this technology, during the excavation phase, the equipment undergoes a torque on the drill rod and a thrust on the excavation screw relatively elevated as the quantity of soil to be compacted during the excavation by the displacer element (FIG. 2) is of significant relevance and exerts also a strong resistance to the advancement of the tool in the soil itself. During the ascent, the excavation is filled by means of injection of concrete which passes through the rods and the tool itself.
The document U.S. Pat. No. 7,494,299 describes an equipment provided with screw tool to which a plurality of hollow, extended and substantially cylindrical shaped rods is applied.
The rods are provided with special endings adapted to vertically connect them. The inner of the rods is destined to be filled with concrete at the end of the anchoring procedures which provide that the rods themselves are disposable as reinforcing structural elements.
However, the internal passage of the rods is not cylindrical and reduces in correspondence with the endings provided with particular inserts for the assembly of the rods themselves.
Furthermore, the rods are designed for carrying inner elements adapted for realizing the rotation which reduce the internal passage but only in correspondence of said endings.